Albayalde said the man's family said he was $80,000 US in debt "due to being hooked in casino gambling."

He said the family's account corroborated the belief "this is not an act of terrorism."

Authorities earlier dismissed the claim of responsibility by the Islamic State in Iraq and Syria (ISIS).

Police in the Philippines say Carlos was a heavily indebted Filipino who was hooked on gambling. (Bullit Marquez/Associated Press)

The Philippines has faced Muslim insurgencies for decades, though much of the violence has occurred in the troubled south, where ongoing battles with Islamic militants are taking place in the southern city of Marawi.

Albayalde said the man had sold off property, including a vehicle, to support his gambling habit of at least several years. His family had grown so concerned they had asked casinos in the capital to ban him since April 3.

The news came after authorities released security footage showing Carlos casually exiting a taxi just after midnight and walking calmly into a vast entertainment and gambling complex like any other visitor. Shortly afterward, he dons a black ski mask, slips on an ammunition vest and pulls an M4 carbine assault rifle out of his backpack.

What follows borders on the surreal: a slow-motion arson attack and robbery so methodical and unhurried, the gunman appears to walk much of the way, even as he exchanges fire with a security guard and flees, slightly wounded, up a stairwell.

At least 37 patrons and employees died, mostly from smoke inhalation as they tried to hide on the second floor, including one the casino's VIP rooms, Albayalde said. The gunman fled to an adjoining hotel, where police say he killed himself.

The video footage shown to reporters Saturday appears to bolster the government's case that this was a botched robbery by a lone attacker with no known link to terrorism. Police said that's exactly why they wanted to release it.

In his first remarks on the assault, Philippine President Rodrigo Duterte said Saturday the attacker was simply "crazy." He questioned what the gunman was going to do with the $2-million horde of poker chips he had tried to haul away. He also discounted any links to ISIS, saying, "The work of the ISIS is more cruel and brutal."

Panicked crowds scatter

Despite some initially contradictory accounts of the chaos, what is known so far appears to back up that claim.

Although the attacker was well armed — Albayalde said he was carrying 90 bullets in three rifle clips — there are no confirmed reports that he shot any civilians. Instead, he fired into the ceilings, scattering panicked crowds, some of whom jumped out windows to escape what they believed to be a terror attack.

Albayalde said the security footage contained a clear motive: the gunman headed straight for a storage room that contained poker chips. He is seen shooting through several thick white doors, breaking down one of them at 12:18 a.m. Friday, only 11 minutes after his arrival. Abayalde suggested he set fires as a diversionary tactic and his next move was to try to get out.

More than 12,000 people were in the complex at the time; most were successfully evacuated.